The development of biomarkers for earlier detection of ovarian cancer will greatly improve survival. Most women present with advanced stage disease with survival rates of roughly 20%. Advances in the field of proteomics now provide the tools necessary to effectively analyze the serum proteome, and the application of such technologies holds great promise for determining novel biomarkers. This proposal outlines methods to comprehensively discover, identify, quantify, and validate a panel of specific and sensitive ovarian cancer biomarkers for early detection. We propose the following Specific Aims: 1. Determine candidate ovarian cancer biomarkers defined by comprehensive biomarker analysis of serum. Emphasis will be placed on refining the most effective overall analytical strategy for comprehensive and reproducible measurements. Spectral peaks that most accurately distinguish cancer vs. control will be identified using high-resolving power technology. Biostatistics and bioinformatics will be used to prioritize candidate markers (according to specificity, sensitivity and predictive value) for further characterization. 2. Identification and absolute quantification of the candidate biomarkers. This will improve reliability and high-throughput capabilities in subsequent validation testing, and the identification of these proteins will contribute further to research into the biologic basis of the disease. We will use accurate mass measurements, tandem mass spectrometry, and non-redundant protein and genome databases applied to distinct selected controls. Furthermore, we will determine the range of values for both normal and cancer serum samples using stable isotope labeled internal standards. 3. Clinical validation of a panel of biomarkers in specific groups of women. Sera from defined cohorts of women will be used to accurately determine the sensitivity, specificity, and predictive values of individual and combinations of candidate markers in all aspects of disease (early/late stage, familial, remission and recurrence) and in large numbers of non-cancer controls.